Method for producing a flanged disk for a spherical roller bearing and a spherical roller bearing having a flanged disk produced according to the method

ABSTRACT

A spherical roller bearing having a flanged disk designed as a hollow body, formed from a straight pipe section that is bent to form a ring having two ring ends that are joined. The ring is shaped into a flanged disk with a desired axial section geometry in a pressing device with a contour tool in a single pass.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is Divisional Application of U.S. Ser. No. 13/389,074filed Feb. 6, 2012, which was a 371 of PCT/DE2010/000903 filed Jul. 29,2010, which in turn claims the priority of DE 10 2009 036 347.5 filedAug. 6, 2009. The priority of these three applications is hereby claimedand these three applications are incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates a method for producing a flanged disk for aspherical roller bearing. Furthermore, the invention relates to aspherical roller bearing with an outer ring, an inner ring and amultiplicity of rollers arranged in at least two rows that are separatedfrom one another by at least one ring-shaped flanged disk.

BACKGROUND OF THE INVENTION

A multiplicity of different embodiments of spherical roller bearings isknown from the prior art. In contrast to normal ball bearings, sphericalroller bearings make it possible to compensate relative movements andalso to have an axial offset between two shafts. During the compensatingaction, however, the rolling bodies are deflected out of their idealpath, and this may lead to a wobbling movement. In order to prevent thisundesirable movement sequence in the case of multiple-row sphericalroller bearings, the rolling bodies are aligned with one another on theend faces by means of what is known as a flanged disk which is arrangedbetween the roller rows.

Since a broad spectrum of the most diverse possible applications inmechanical engineering is covered by spherical roller bearings, suchflanged disks have to be produced in a wide range of variation in termsof their dimensions and also in large quantities. The flanged disks arenowadays generally produced from portions of comparatively thick-walledtubes, these portions subsequently being machined further by cutting.However, this procedure is not practicable if the flanged disks requiredhave special dimensional ratios, and therefore, in individual cases,solid round material has to be resorted to as initial material. Use ofsolid round material necessitates considerable scrap or waste, however,along with a high outlay in terms of manufacturing and cost.Furthermore, flanged disks made from solid material increase the weightof the spherical roller bearing thereby formed.

A two-row spherical roller bearing is known from DE 29 04 368. In thisspherical roller bearing, the two rolling body rows are separated fromone another by means of a loose guide ring. However, the guide ring isproduced from a solid material, and therefore the abovementioneddisadvantages of the prior art also apply to this embodiment.

SUMMARY OF THE INVENTION

The invention is directed to an improved method for producing a flangeddisk for a spherical roller bearing, which permits simple manufacture,while at the same time reduces the scrap of the initial material, andallows for the production of weight-optimized flanged disks which inturn results in a reduction in the mass of the bearings equipped withthem. Moreover, the invention is directed to a spherical roller bearing,which has a flanged disk improved in this way.

The method of the present invention broadly comprises bending aninitially straight pipe portion into a ring having two ring endsseparated by a gap. Two ring ends are then joined together thermally,and the closed ring is subsequently shaped into a flanged disk, whichhas an axial sectional geometry deviating from the circular shape. Themethod gives rise to negligibly low scrap from the initial materialused. Apart from this, the cost-intensive cutting process necessaryhitherto is dispensed with. Furthermore, the flanged disk, produced as ahollow body according to the method, has a significantly reduced weight,as compared with solid flanged disks with the same dimensions, thusopening up completely new areas of application. Moreover, a broadspectrum of flanged disks for the most diverse spherical roller bearingapplications can be produced with a limited stock of tubes havingstandard dimensions.

The initial material for the method according to the invention istherefore an initially straight tube portion which, in a first methodstep, is bent or shaped into a ring having two ring ends separated by anarrow gap. The requisite length of the tube portion first to be cut tolength from the initial tube depends on the required dimensions of theflanged disk to be produced from it by shaping. During this firstshaping process, the original annular cross-sectional geometry of thetube portion is initially still approximately preserved. To prepare fora subsequent welding process, it may be necessary, in particular, tosubject the two ring ends to mechanical retreatment, such as, forexample, cut to length and/or lathe turning.

In a second method step, the ring ends are connected to one another toform a ring closed on itself which, in a third method step, is shapedinto a flanged disk having an axial sectional geometry deviating fromthe circular shape. This second shaping process preferably takes placein a single pass in a press, using the shaping or contouring toolsrequired for achieving a desired cross-sectional geometry. The ring endsare preferably joined together by welding.

According to an advantageous development of the method, there isprovision whereby the flanged disk is given by the shaping process anapproximately trapezoidal axial sectional geometry in which a surfacearea formed radially on the inside is axially shorter than a surfacearea formed radially on the outside. The external configuration of theflanged disk provided according to the invention consequentlycorresponds essentially to the appearance of the flanged disks knownalready from the prior art, and therefore the flanged disk producedaccording to the method can be employed in the known spherical rollerbearings without further structural changes.

In a further advantageous refinement of the method, at least one ventingbore is introduced into the straight tube portion or into the ring. As aresult, on the one hand, the welding gases occurring during the thermaljoining process can escape in a depressurized manner. On the other hand,the subsequent shaping process in the pressing tool is facilitated,since any changes in volume as a result of the change in geometrycarried out on the ring do not lead to pressure rises.

According to a further advantageous development of the method, there isprovision whereby the straight tube portion has a wall thickness ofbetween 1.0 mm and 3 mm before the shaping operation. Said dimensions ofthe tube portion ensure that the ring formed from the tube portion isshaped sufficiently easily, preferably in one pressing step, into theflanged disk having a desired cross-sectional geometry. Furthermore, thestated wall thicknesses of the tube portion enable the straight tubeportion to be bent, essentially free of kinks, into the required ringpreform having inside and outside diameters customary for flanged disks.

According to a development of the method, there is provision where anoutside diameter of the straight tube portion lies between 15 mm and 30mm.

As a result, flanged disks having the most frequently requiredcircumferential lengths of the approximately trapezoidal cross-sectionalgeometry usually needed can be shaped out of the straight tube portionor the ring.

In a further beneficial refinement of the method, the two ring ends arejoined together by means of electric resistant welding. This ensuresthat the butt weld seam required between the two ring ends is producedespecially simply in terms of process engineering. It is also possible,however, to connect the two ring ends to one another by means of acommon sealing plug which is pressed into the end-face cavities of thering ends.

According to a further development of the method, there is provisionwhereby the thermally joined ring is shaped in a press, preferably in asingle pass, by means of a contouring tool into a flanged disk havingthe desired cross-sectional geometry. As a result of the single-passshaping process by means of a suitable contouring tool or pressing tool,the flanged disks can be manufactured by means of the method with shortcycle times, with high dimensional accuracy and in large quantities,using standard automatic presses.

The invention therefore also relates to a spherical roller hearing withan outer ring, an inner ring, and a multiplicity of rollers, which havea convex tread, received between them in at least one roller cage. Therollers are arranged in at least two rows, and the at least two rollerrows being separated from one another by at least one ring-shapedflanged disk. Contrary to the prior art, there is provision for theflanged disk to be a hollow body.

Since the flanged disk is a hollow body, the spherical roller bearingequipped with it has reduced mass, as compared with known solutions.Moreover, the flanged disk can be produced cost-effectively and in largequantities in an energy-efficient manner, while the scrap from theinitial material used is minimized.

In an advantageous refinement of the spherical roller bearing, thehollow body has an approximately trapezoidal axial sectional geometry,in which a surface area formed radially on the inside is axially shorterthan a surface area formed radially on the outside. As a result, theflanged disk according to the invention corresponds to the conventionalcross-sectional geometry of known flanged disks, and therefore, as arule, no modifications have to be carried out to the previous design ofspherical roller bearings.

In further advantageous refinements, the hollow body has a wallthickness of less than 3.0 mm and at least one venting bore.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below by means of theaccompanying drawing in which:

FIG. 1 shows an axial section through a spherical roller bearing havinga flanged disk according to the prior art,

FIG. 2 shows a perspective illustration of a detail of a flanged diskdesigned according to the invention as a hollow body, with a view of itsaxial sectional geometry,

FIG. 3 shows a perspective view of an initially straight tube portionbent into a ring with free ends, as a ring preform, and

FIG. 4 shows a perspective illustration of the ring preform welded andshaped into the flanged disk.

DETAILED DESCRIPTION OF THE INVENTION

The same structural elements have in each case the same referencenumeral in the drawing.

FIG. 1 accordingly shows a longitudinal section through an upper part ofa two-row spherical roller bearing 1 with a flanged disk 12 in a knownembodiment. The spherical roller bearing 1 comprises, inter alia, anouter ring 2 and an inner ring 3, between which rollers 4, 5 having ineach case a convex tread 6, 7 are arranged in two rows 8, 9 runningparallel to one another. The inner ring 3 of the spherical rollerbearing 1 is mounted on a bearing shaft 10 indicated. The rollers 4, 5are guided in at least one roller cage 11 which has a multiplicity ofpockets, not illustrated in any more detail in the drawing, forreceiving the rollers. Positioned between the two rows 8, 9 having therollers 4, 5 is a flanged disk 12 with an approximately trapezoidalaxial sectional geometry, to which planar roller end faces 13, 14 of thetwo rollers 4, 5 are adjacent on both sides, in order to preventundesirable wobbling movements of the latter. Such wobbling movementsarise, for example, when a longitudinal axis 15 of the bearing shaft 10,including the inner ring 3, is pivoted in relation to the outer ring 2or, conversely, the outer ring 2 is pivoted in relation to the innerring 3 and the bearing shaft 10. The flanged disk 12 is produced in aknown way from a solid material, for example from a steel or high-gradesteel alloy, and consequently has a relatively high weight.

FIG. 2 shows a detail of a flanged disk produced by means of the methodaccording to the invention. A flanged disk 16 is designed as aring-shaped hollow body 17 closed on itself and having an approximatelytrapezoidal axial sectional geometry. The flanged disk 16 has, interalia, two planar flanks 18 and 19 which run radially opposite to oneanother at a low inclination and which serve as bearing surfaces for endfaces 13, 14, not illustrated in FIG. 2, of the rollers 4, 5 in aspherical roller bearing 1. Two parallel ring surfaces 20, 21 adjoin thetwo flanks 18, 19 radially on the outside and are connected to oneanother via to radially outer surface area 22. Lower ends, notdesignated, of the axial flanks 18, 19 are connected to a radially innersurface area 23 in each case via an oblique face. This radially innersurface area 23 serves for supporting the flanged disk 16 on the innerbearing ring 3 of the spherical roller bearing 1.

The flanks 18 and 19, the two ring surfaces 20 and 21 and the surfaceareas 22 and 23 form an approximately trapezoidal axial sectionalgeometry of the flanged disk 16, said axial sectional geometry beingclosed on itself and being generated by means of a simple shapingprocess out of a tube portion bent into a ring and having an annularcross-sectional geometry (see FIGS. 3 and 4). In particular,transitions, not designated, between the flanks 18, 19 and the innersurface area 23 and transitions between the ring surfaces 20, 21 and theouter surface area 22 are not angular, but are preferably rounded, andare in this case designed with a radius of less than or equal to 1.0 mm.

The wall thickness 24 of the flanged disk 16 may vary in regions andpreferably amounts to less than 3.0 mm. An approximate (mean)circumferential length 25 of the axial sectional geometry of the flangeddisk 16 is composed, depending on the shaping process, of the sum of thelengths of the two lateral flanks 18 and 19, of the ring surfaces 20 and21 and of the inner and outer surface areas 22, 23, including thelengths, not designated in any more detail, of the transitions. Theshaped-out flanged disk 16 has an outside diameter 26 and an insidediameter 27 which are adapted to the respective dimensions of thespherical roller bearing into which the flanged disk is to be integrated(see FIGS. 1 and 4).

The method according to the invention for producing the flanged diskaccording to FIG. 2 will be explained in more detail by means of FIGS. 3and 4 to which reference is made as the description proceeds.

The starting point of the method is a straight tube portion, notillustrated, which, in a first method step, as indicated by way ofexample in FIG. 3, is shaped into an approximately circular, that is tosay essentially toroidal ring 28 having an annular cross-sectionalgeometry. The tube portion is a portion of any length of a tube havingstandard dimensions. Between the two ring ends 29, 30, a narrow gap 31occurs due to an unavoidable springback effect after cutting to lengthand bending round. In the region of the gap 31, the two ring ends 29, 30are joined together in a second method step, preferably by means of anelectric resistance welding, so as to provide a butt weld seam, notillustrated. Alternatively to this, the two ring ends 29, 30 may also bejoined together by means of other suitable thermal joining methods, forexample by laser welding or the like.

Before thermal joining, it is usually necessary to subject the region ofthe ring ends 29, 30 to mechanical retreatment, for example by detachinga short piece in the region of the two ring ends 29, 30 and/or bylathe-turning the ring ends 29, 30. Before the actual welding operation,at least two continuous cylindrical venting bores 32, 33 are introducedinto the ring 28 by drilling or punching, preferably in the region ofthe ring ends 29, 30. On the one hand, these venting bores 32, 33prevent excess pressure from occurring in the ring 28 as a result of thewelding gases arising due to the thermal joining process. On the otherhand, the venting bores 32, 33 during the subsequent process of shapinginto the flanged disk 16, in which a change in volume of an inner spaceof the ring 28 generally also occurs, prevent the situation where excesspressure within the ring 28 arises. Before the shaping process, anoutside diameter 34 of the tube portion lies in a range of between 15 mmand 30 mm, but may have dimensions deviating from this, depending on thestructural requirements to be satisfied by the associated sphericalroller bearing.

The final shaping of the welded ring preform 28 into the flanged disk 16according to FIGS. 2 and 4 takes place in a third method step in apress, not illustrated in the drawing, using corresponding contouringtools or shaping tools, preferably in a single step. As is clear fromFIG. 4, an axial sectional geometry 35 of the flanged disk 16 producedhas an approximately trapezoidal configuration, as regards the detailsof which reference is made to the explanations already given in thedescription of FIG. 2. The venting bores 32, 33 may, if necessary, behermetically closed or sealed again after the end of the productionprocess.

The outside and the inside diameter 26, 27 of the shaped-out flangeddisk 16 correspond in each case to the structurally demanded dimensionalstipulations of the spherical roller bearing into which the flanged disk16 is to be inserted. Both the outside diameter 26 and the insidediameter 27 of the flanged disk 16 are in this case dependent on alength 36 of the ring 28 or of the initially straight tube portion, onits outside diameter 34 and on the type and degree of the shapingprocess employed in the individual case. Said dimensions therefore haveto be predetermined, with reference to the shaping process, by means ofsuitable numerical simulation processes, so that the cross-sectionalgeometry 35 of the flanged disk 16 to be shaped out and its outside andinside diameters 26, 27 conform exactly structurally to the stipulatedboundary conditions of the spherical roller bearing.

LIST OF REFERENCE SYMBOLS

-   1 Spherical Roller Bearing-   2 Outer Ring-   3 Inner Ring-   4 Roller-   5 Roller-   6 Tread of the Roller-   7 Tread of the Roller-   8 Row with Rollers-   9 Row with Rollers-   10 Bearing Shaft-   11 Roller Cage-   12 Flanged Disk-   13 Roller End Face-   14 Roller End Face-   15 Longitudinal Axis, Bearing Shaft-   16 Flanged Disk-   17 Hollow Body-   18 Flank-   19 Flank-   20 Ring Surface-   21 Ring Surface-   22 Outer Surface Area-   23 Inner Surface Area-   24 Wall Thickness-   25 Circumferential Length-   26 Outside Diameter of the Flanged Disk-   27 Inside Diameter of the Flanged Disk-   28 Ring Preform-   29 Ring End-   30 Ring End-   31 Gap-   32 Venting Bore-   33 Venting Bore-   34 Outside Diameter of the Ring 28-   35 Cross-Sectional Geometry (approximately trapezoidal)-   36 Length (straight tube portion or ring)

The invention claimed is:
 1. A spherical roller bearing, comprising: anouter ring; an inner ring; at least one roller cage; a plurality ofrollers, which have a convex rolling contour, arranged between the outerring and the inner ring in the roller cage in at least two rows; and atleast one ring-shaped flanged disk arranged to separate the two rows ofrollers from each other, wherein the flanged disk is a hollow bodyincluding a curved tube portion having an axial cross-section completelysurrounding a hollow space.
 2. The spherical roller bearing as claimedin claim 1, wherein the hollow body has a substantially trapezoidalaxial cross-section such that a surface area formed radially on aninside of the hollow body is axially shorter than a surface area formedradially on an outside of the hollow body.
 3. The spherical rollerbearing as claimed in claim 1, wherein the hollow body has a wallthickness of less than 3.0 mm.
 4. The spherical roller bearing asclaimed in claim 1, wherein the hollow body has at least one ventingbore.
 5. The spherical roller bearing as claimed in claim 1, wherein theaxial cross-section of the tube portion is substantially trapezoidal andcompletely surrounds a substantially trapezoidal axial cross-section ofthe hollow space.
 6. The spherical roller bearing as claimed in claim 5,wherein tube portion includes two planar flanks running radiallyopposite to one another serving as bearing surfaces for end faces of therollers, the tube portion further including a radially outer surfacearea and a radially inner surface area, the hollow space being formedbetween and inside of the two planar flanks, the radially outer surfacearea and the radially inner surface area.
 7. The spherical rollerbearing as claimed in claim 6, wherein the radially inner surface areasupports the flanged disk on the inner ring.
 8. The spherical rollerbearing as claimed in claim 7, wherein the radially outer surface areasupports the flanged disk on the outer ring.
 9. The spherical rollerbearing as claimed in claim 6, wherein the two planar flanks, theradially outer surface area and the radially inner surface area areconnected to each other by rounded transitions.